The attack in Buenaventura ripped into a local attorney general’s office and damaged taxis passing on the street. While authorities say they suspect leftist FARC rebels are responsible, they have not ruled out the possibility it was a retaliation against the office’s drug investigations.

The bombing in Colombia’s largest port comes ahead of the country’s May presidential elections to replace Alvaro Uribe. His stiff crackdown on the Marxist Revolutionary Armed Forces of Columbia (FARC) since he took office in 2002 has earned him popularity, but guerilla attacks remain a problem, Christian Science Monitor reported.

Colombia's long war has ebbed since President Alvaro Uribe came to power in 2002 and sent troops to take on rebels and drug barons. But guerrillas are still fighting in rural areas and the country remains the world's top cocaine exporter.

"We cannot let our guard down," Uribe said after the bombing, without blaming any armed group. "We had recovered a lot in Buenaventura, this act shows we cannot allow ourselves to be too confident."

Nine people were killed and another 50 wounded in the blast, the National Police said, Reuters informed.

Colombian President Alvaro Uribe has condemned the attack without making a reference to any special group and warned against complacency in the campaign against guerrillas vying for more control over the past 46 years, according to Press TV.